"Samuel also said unto Saul, 'The Lord sent me to anoint thee to be king over His people, over Israel. Now therefore hearken thou unto the voice of the words of the Lord.
Thus said the Lord of hosts, 'I remember that which Amalek did to Israel, how he laid wait for him (ambushed) in the way which he came up from Egypt. Now go and smite Amalek, and utterly destroy ALL that they have, and spare them not. But slay both man and woman, infant and suckling, ox and sheep, camel and ass'."
(Saul obeys God and attacks in verses 4-7)
"And he (Saul) took Agag the king of the Amalekites ALIVE, and utterly destroyed all the people with the edge of the sword. But Saul and the people SPARED AGAG, and the BEST OF THE SHEEP, AND OF THE OXEN, AND OF THE FATLINGS…
Then came the word of the Lord unto Samuel saying, 'It repenteth (I am sorry) Me that I have set up Saul to be king. For he is turned back from following Me, and hath not performed My commandments'…"
(the next morning, Samuel goes to Saul to tell him God is displeased)
"And Samuel came to Saul. And Saul said unto him, 'Blessed be thou of the Lord. I have performed the commandment of the Lord.'
And Samuel said, 'What meaneth then this bleating or the sheep in mine ears, and the lowing of the oxen which I hear?'
And Saul said, 'They have brought them from the Amalekites for the people spared the best of the sheep and of the oxen, to SACRIFICE UNTO THE LORD THY GOD'…
(vs 22) And Samuel said, 'Hath the Lord as great delight in burnt offerings and sacrifices, as in obeying the voice of the Lord? Behold, TO OBEY IS BETTER THAN SACRIFICE, and to hearken than the fat of rams'." 1 Samuel 15:1-22